Hearing aid



E) M. WILUAMS 2,813,933

HEARING AID Nov. 19, 1957 Filed May 26, 1953 2 Sheets-Sheet 1 lNvENToREVERARD MWILLIAMS Nov. 19, 1957 E. M. WILLIAMS 2,813,933

' HEARING AID Filed May 2e, 1953 2 Sheets-sheet INVENTOR EVERARD M.WILLIAMS @if www Patented Nov. i9, i957 HEARING Aro Everard MtWilliams,.Pittsburgir, Pa., assigner to Alan M; Sfcaife, PittsburghmPa.

Application-Win26, 1953, Serial No. 357,556

3 Claims. (Cl. 179-107) This` invention.relatestohearingaids and is inthe nature of an improvement ,over` the invention of vUnited StatesPatent No. 2,613,282. In that patent there is disclosed a hearing vaidcharacterized byits inconspicuousness and lcompactness shown as .beingcontained within a support having. the general conguration of aspectacleframe. In. that hearing aid thesoundvibration receiving portion isdisposedin the bridge of the spectacle frame. A" soundreproducer iscarried by the support near the ear of the user and means are providedWherebysound vibrations ,received bly the` sound vibration receivingportion are convertedinto audible sounds in the sound reproducer, thehearing aid being conned .entirely within the support and having noexterior Wires, ear plug or connections offany kind.`

The hearing aid of" said patent is` satisfactory` but requires'thebridgeportionv of thesupportto be undesirably large "and also has limitationsas to capacityl and` life because all of the operatingparts must beconned within very smallfspaces.

I providel a hearing aidfin which I`utilize. a `iirstunit wornV uponthey users bodyV converting sound vibrations into electric Yand-magnetic eld 'oscillations together with.

a second unit physically entirely separate from and unconnected with therst unit Worn upon the users head. receiving oscillations from the firstunitan'd converting the same into audible sounds adjacent theusers ear.

It has previously beenproposed to provide a hearing .aid having twoseparateunits, one carried bythe user upon his torso andthe otherconstituting an ear; plug Without'co-nnecting Wires, the usersbody beingrelied upon as a portion ofthe conducting circuit rendering the deviceoperable. This requires that there be two body electrodes in firmcontact with the `body of the user, one at the torso and .the other atthe ear. Sucha hearing aid is unsatisfactory, iirst, because of thenecessity'ofthe provision of the b'ody electrodes and, second, becausethe ear plug is unsightly and makes known the fact that the user is hardof'hearing. Special clothing must be provided to enable applicationofthefbody electrode to the torso of the user While the microphone isdisposed outside the clothing.

My hearing aiddoes not employ the body of the user as a portion Otanelectrical circuit necessary to operation of the hearing aid .and hencekrequires-no body electrodes and no special clothing, and r alsorrnyhearing aid dispenses with an ear plug: It has all `ofthe advantages ofthe hearing-aid ofPatentNo. 2,613,282 yand the additional advantages:that ay smaller andless conspicuous bridge portion may be provided inthe support which has the general configuration ofra spectacle frameand'that a much-'more powerfulrunit for receivingand converting soundvibrations maybe employed since that unit visvvorn uponv the` usersbodybelow ythe .head 'and hence may be of substantial rsize.y Such `unitmaybe concealed'fbeneath theV outerV clothing tof :the ruser; `andlit`may befcompletely outof contactwith the` usersfbody. Actually such unitmay. be .-of considerablysmaller size Lthan ay conventional thearingfaid which is; Worn upon the users body and connected by Wireswith an ear plug or bone conducting unitzcarried .by a headclamp.

. My hearing aid'may take different forms, one form 5 comprising-meansWorn upon the users body converting sound vibrations intoan-oscillating-electricfield and means physically entirely separate fromand unconnected Withtherst mentioned means Worn upon the users headv.intersecting the electric iield created by the iirst l() mentionedmeans and converting the electrical oscillations. induced in itsconductors hy this field to audible soundsadjacent' the users ear, andanother form comprising means Worn upon the users body converting soundvibrations into, an oscillating magnetic eld and meansk physicallyyentirely separate from and unconnected with the first mentioned meansWorn upon the users head intersectingmagnetic. flux in said eld andconverting electrical oscillationsinduced in its conductors by thisfield lations that 'they are. not reliedupon for operation of thekhearing aid although they might beso employed.

' The sound converting means of my hearing, aidmay include: a conductorWorn at least partially about the users neck., the conductor need notextend completely about the users neck but should have portionsextending at least` to" the sides of the neck. When the magnetic fieldis utilized-the conductor should extend completely .about the usersneck. I find, it convenient to disposev the con- 40 ductor in a necktie.The conductor may take Various forms, one4 preferred form being a braidof Phosphor 'bronze which has the desired electrical properties and isvery'lexible so that it maybe deformed and knotted with the lnecktie.`downwardly from theI neck is connected With a microphone uni-t. Themicrophone unit may be Worn upon the clothingof the user completely outof contact with the users-body.

-Sound vibrations are converted into electric and magnetic iieldosciliations in the conductor which extends at least `partially aboutthe users neck and those oscillations *iny turn produce in conductors inthe temples of the support worn on the users head a current ofelectricity Which isfconverted into audible sounds adjacent the usersear. The conductors in the temples of the support intersect theelectricorimagnetic iield emanating from `the conductor Whichisdi'sposedat least partially about the users neck whereby a current flow isinduced in the former.

Other details, objects and advantages of the invention @Q will: becomeapparent as thefollowing description of certain present preferredembodiments thereof proceeds. l In theaccompanying drawings I have showncertain presentpreferred embodiments of the invention in which: Figure 1is an electrical diagram or one form of the unitof Vthe hearing aidwhich is adapted to be Worn upon the users body;

Figure 2'is asomewhat diagrammatic illustration of onerform of the unitof the hea-ring aid which is adapted p Indeed, electromagnetic waves of.

When the .oscillating electric field is utilized The end of theconductor extending' Figure 4 is an electrical diagram of the hearingaid unit shown in Figures 2 and 3;

Figures 5 and 6 are diagrams illustrating the operation of the form ofhearing aid shown in Figures l4; and

Figure 7 is a diagram illustrating the operation of another form of myhearing aid.

The means for converting sound vibrations into electric and magneticfield oscillations which is worn upon the users body is illustrateddiagrammatically in Fig. 1. In that figure there is shown a microphone2, an audio amplifier 3, an audio modulator 4, an oscillator 5 and aconductor designated generally by reference numeral 6. The microphone 2,the audio amplifier 3, the audio modulator 4 and the oscillator 5 may beconnected in conventional manner as well known to those skilled in theart and may be disposed within a small and inconspicuous case. Theconductor 6 extends from the oscillator out of the case as shown inFigure 1 and has two branches 7 and 8 extending alongside the users neckat opposite sides thereof. The branches 7 and 8 may be connectedtogether at the rear of the users neck forming a complete loop if themagnetic field is to be utilized for operation of the hearing aid. Ifthe electric field is to be utilized it is not necessary that thebranches 7 and 8 be joined together at the rear of the users neck, thosebranches having the desired function because they are respectivelygenerally below and parallel to the conductors in the temples of thesupport worn on the users head as will presently be described.

I find it most practical to incorporate the conductor 6 in a necktie andto make the conductor continuous lengthwise of the necktie. While, asindicated above, a continuous conductor capable of forming a closed loopis required when the magnetic field is to be utilized a1- though notrequired when the electric eld is to be utilized, such a continuousconductor may be employed in either case. I desirably dispose a Phosphorbronze braid inside the necktie and after the necktie has been tied Iconnect together the ends of the braid at the ends of the necktie andconnect the same to the oscillator. Sound impinging on the microphone 2causes weak audio frequency currents which are amplified by the audioamplifier and fed to the audio modulator which modulates thehigh-frequency carrier produced by the oscillator. Modulated carriercurrents are fed to the conductor 6.

The portion or unit of the hearing aid which is worn upon the users headand which has the general configuration of a spectacle frame is shown inFigures 2 and 3. The support is designated generally by referencenumeral 9 and as shown in Figures 2 and 3 has the general conguration ofa spectacle frame. It has spaced apart bearing portions 10 adapted tobear on the nose of the user. It has opposed temples 11 and 12 extendingto positions adjacent the ears of the user and having slightly curvedend portions 13 and 14 respectively which are adapted to lie atop theears and press against the users head, as against the mastoid bone, andto cooperate with the portions lll to maintain the support in positionon the head. The portions 10 are integral or connected with a front part15 of the support 9. The front part 15 has two portions 16 shaped aslens frames connected by a bridge 17. When the portions 10 bear on theusers nose the bridge 17 is disposed at the front of the upper portionof the nose as is conventional.

The sound reproducer is disposed in the curved end portion 14 of thetemple 12 of the support 9 and is shown diagrammatically at 18 in Figure2. The sound reproducer 18 is of the bone conduction type and is by thetemple 12 of the support pressed against the mastoid bone generallyabove the users left ear. The sound reproducer is suitably mounted inthe portion 14 so that when it is activated it will in turn through themastoid bone of the user activate the auditory nerve of the user or inother words produce audible sounds adjacent the vusers ear. Theprinciple of operation of the bone conduction type sound reproducer 18is the same as the principle of operation of any bone conduction typesound reproducer but the sound reproducer is rendered inconspicuous or,indeed, invisible by disposing it within the support.

The power unit for the portion of the hearing aid carried by the support9 is disposed within the temple 11 of the support and may comprise twobatteries 19 and 20 electrically connected as will presently bedescribed. The batteries are of appropriate capacities, the battery 19desii-ably having a voltage of the order of 3 volts and the battery 20desirably having a voltage of the order of 30 volts. The function of thepower unit consisting of the batteries 19 and 20 is to supply thenecessary electrical energy to operate the portion of the hearing aidcarried by the support 9.

The support 9 carries, desirably in the bridge 17, a detector designateddiagrammatically by reference numeral 21 in Figures 2 and 3 and whichwill be described in detail below. The detector may be quite small andcompletely concealed within a normal sized spectacle bridge, obviatingthe necessity of providing an abnormal and unsightly bridge of largesize containing a microphone as in United States Patent No. 2,613,282.

Three transistors 22, 23 and 24 and two transformers 25 and 26 may bedisposed within the temple 12 as shown in Figure 2. A switch 27 forclosing and opening the electrical circuit is provided in the temple 11,the switch comprising a turnable ring operable by the fingers of theuser, the circuit being closed when the ring is in one rotative positionand being open when the ring is in another rotative position. A similarring 28 is provided in the temple 12 for volume control. The requiredconductors are not shown in Figures 2 and 3 but are disposed within thesupport 9. Preferably the support is hermetically sealed; at least thetransistors should be hermetically sealed to exclude moisture.

The portion of the hearing aid Worn upon the users head is, in general,like that shown in United States Patent No. 2,613,282 and reference ismade to that patent for details of construction which do not constitutethe present invention.

One electrical circuit which may be employed in the portion 0f thehearing aid worn upon the users head is shown in Figure 4. The detectorunit 21 comprises a resistance unit 29, a capacitance unit 30 inparallel with the resistance unit 29 and a rectifier 31 connected asshown in Figure 4. The voltage is fed by way of chokes 32 and 33 toconductors 34 and 35, respectively. A choke 36 is also provided toconstitute a return path of direct current components passing throughthe detector.

The conductor 35 extends to the emitter electrode 37 of the transistor22. A conductor 38 extends from the collector electrode 39 of thetransistor 22 to one side of the transformer 25. The circuit throughthat side of the transformer 25 is completed by a conductor 40 whichextends to a conductor 41 which extends to the switch 27 and acorresponding conductor 42 which extends from the switch 27 to thebattery 20. The batteries 20 and 19 are connected in series by aconductor 43.

The 4Opposite side of the transformer 25 is connected through aconductor 44 with a contact member 45 operated by the ring 28cooperating with a resistance pad 46. A conductor 47 from the resistancepad 46 is connected to the transformer 25 at 48. The 'conductor 47 isconnected with the conductor 34 which extends to the switch 27. Aconductor 49 extends from the switch 27 to the battery 19.

The transformer 25 is connected with the emitter electrode 50 of thetransistor 23 by a conductor 51. The collector electrode 52 of thetransistor 23 is connected with the transformer 26 by a conductor 53. Aconductor 54 leads from the transformer 26 to the conductor 41.

The transformer 26 is connected with the emitter electrode 5S of thetransistor 24 by a conductor 56. The collector electrode 57 of thetransistor 24 is connected agei'agaa with the soundreproducerlA byacoductor 5S. conductor"59"leadsfrom the-soundreproducer 18toithe'conductor 41. 1

l "The ground electrode-60 ofthe transistor 22, 'thefground electrode-61 `of the transistor323'rlandfthe groundelectrode 62*ff`the4transistor Y24--are grounded, A ask is thef conductor 43. A groundconductor may connect the ground electrodes 60, 61 and 62 and theconductor 43.

The unit worn on the users head serves to pick up a high frequencyvoltage from the branches 7 and 8 of the conductor 6. A voltage isdeveloped in the detector 21 by reason of the electric field couplingbetween the branches 7 and 8 -of the conductor 6 and conductors 63 and64 disposed within and extending lengthwise of the temples 11 and 12,respectively. The detector demodulates the high frequency signal anddelivers an audiblefrequency voltage output to conductors 321/2 and331/2. Such audio-frequency voltage is conducted through conductor 35 tothe emitter electrode 37 of the transistor 22. Changes in currentbetween the emitter electrode 37 and the ground electrode 60 of thetransistor 22 produce changes in current in the transistor path betweencollector electrode 39 and ground electrode 60 which by virtue of therelatively high voltage of the battery have energy greater than thatexerted by the current in the conductor 35, emitter electrode 37 andground electrode 60. Transformer reduces the voltage of the amplifiedspeech currents from transistor 22 to match the resistance of thecircuit between the emitter electrode and ground electrode 61 oftransistor 23. The resistance pad 46 acts in the nature of a rheostat tovary the amplitude of the electrical vibrations reaching transistor 23in order to control the volume of current employed for operating thehearing aid and hence the loudness of the sounds emanating from thesound reproducer 18. The energy of the electrical impulses originatingin the path between the collector electrode 52 and the ground electrode61 of the transistor 23 derived from the battery 20 is fed to the soundtransformer 26 which matches the impedance between the output of thetransistor 23 and the input of the transistor 24 in a manner well knownin the art. The output of transistor 24 derived from the circuitincluding collector electrode 57, sound reproduc-er 18, battery 20 andground electrode 62 represents impulses originating in detector 21 sothat the users auditory nerve is activated.

I shall now explain how voltage is developed in the detector 21. Thiswill be done with reference to Figure 5 which is a diagram showing therelationship between the units carried upon the users body and carriedupon the users head, respectively, and with reference to Figure 6 whichis an equivalent electrical circuit diagram.

Stray capacitances are inherent between the branches 7 and 8 of theconductor 6 and the respective conductors 63 and 64. The outer end ofthe conductor 63 is designated a and the outer end of the conductor 64is designated b. The inner end of the conductor 64 is designated c andthe inner end of the conductor 63 is designated d. These same lettersare uniformly applied in all of Figures 4, 5 and 6. The outer end of thebranch 7 is designated a and the outer end of the branch 8 is designatedb. The inner end of the branch 8 is designated c and the inner end ofthe branch 7 is designated d. The stray capacitances are designatedsymbolically in Figure 5 as follows: 65 between a and a; 66 between band b; 67 between c and c; and 68 between d and d'.

Figure 6 shows in addition to the stray capacitances above mentioned theself-inductances of the conductors as follows: the self-inductance 69 ofthe conductor 63; the self-inductance 70 of the conductor 64; theself-inductance 71 of the branch 8 of the conductor 6; and theself-inductance 72 of the branch 7 of the conductor 6. The source ofvoltage in the conductor 6 is indicated' diagrammatically in Figure 6 at73. The voltage across source 73 tends to cause current to flow from cto C,

throughfdetector'iZl toit and back via d to $73. `r`l`his `fp`a`th hasa"1"elatively"hi'gh impedancel to current and the result is a very smallvoltage across detector 21. The voltage across source 73,also.tends tocause current to ow from Yc"'tl1rou`gh inductance`71' to bl and thencefrom b through straycapacitancef-66to b,?thence via inductance70-tovc,throu gh detector 21 tod, thence via\inductance 69 to a, thencevia stray capacitance 65 to a' and thence via inductance 72 to d andback to 73. The reactances of the inductances and stray capacitances areopposed in accordance with well known properties of these circuitelements so that the second mentioned path of current fiow has a lowerimpedance, resulting in fairly large voltages across detector 21. Thishigh frequency amplitudemodulated voltage is detected by the combinationof resistance 29, capacitance 30 and rectifier 31 (Fig. 4) so that anaudio-frequency voltage and steady direct current component appearacross points 74 and 75. This voltage is fed by way of chokes 32 and 33to the amplifier. These chokes serve to keep undesired high-frequencyvoltages induced in the amplifier leads in a manner similar to thevoltages described above from interfering with the operation of theamplifier. Choke 36 serves to provide a return path for direct currentcomponents passing through the detector.

Figure 7 is a diagram illustrating the operation of a hearing aid inwhich a magnetic field is relied upon for operation. In Figure 7 thebranches 7 and 8 of the conductor-.6 are connected together behind theusers neck as shown at 76. The unit carried upon the users head operatesas a closed circuit consisting of inductance 69, detector 21, inductance70 and stray capacitance 77 behind the users head. Current flows in theloop 73--7-76- 8-73 due to the voltage at 73. Such current flow causesthe setting up of a magnetic field which is intersected or pierced bythe conductors 63 and 64; in other words, lines of magnetic flux fromthe magnetic field link the circuit of the unit worn upon the usershead. Voltages are induced in that circuit and appear at the detector21.

While I have shown and described certain present preferred embodimentsof the invention it is to be distinctly understood that the invention isnot limited thereto but may be otherwise variously embodied Within thescope of the following claims.

I claim:

l. A hearing aid comprising means worn upon the clothing of the usercompletely out of electrical contact with the users body, said meansconverting sound vibrations into electric and magnetic fieldoscillations, and means physically entirely separate from andunconnected with the first mentioned means mounted in a support havingthe general configuration of a spccacle frame Worn upon the users headreceiving oscillations from the first mentioned means and converting thesame into audible sounds adjacent the users ear.

2. A hearing aid comprising means worn upon the clothing of the usercompletely out of electrical contact with the users body, said meansconverting sound vibrations into electric and magnetic fieldoscillations, and means physically entirely separate from andunconnected with the first mentioned means comprising a support havingthe general configuration of a spectacle frame worn upon the users headand mechanism therein, said second mentioned means receivingoscillations from the first mentioned means and converting the same intoaudible sounds adjacent the users ear.

3. A hearing aid comprising means including a conductor worn at leastpartially about the users neck completely out of electrical contact withthe users body, said means converting sound vibrations into electric andmagnetic field oscillations, and means physically entirely separate fromand unconnected with the first mentioned means mounted in a supporthaving the general configuration of a spectacle frame worn upon theusers head re- Cal'.

References Cited in the le of this patent UNITED STATES PATENTS EichornNov. 12, 1929 Perlman May 18, 1943 Rosenberg -n July 12, 1949 HalsteadSept. 11, 1951 Potter r Sept. 25, 1951 Hathaway et a1. Oct. 30, 1951Scaife Oct. 7, 1952

